Common audio and video encoding standards, such as MPEG-1, Layer 3 (audio) and MPEG-2, or H.264 (video), significantly compress audio and video data, respectively. This allows for the transmission and storage of the audio and video data with less bandwidth and memory.
In general, the video encoding standards operate on the pictures forming the video. A video comprises a series of pictures that are captured at time intervals. When the pictures are displayed at corresponding time intervals in the order of capture, the pictures simulate motion.
Generally, audio signals are captured in frames representing particular times. During playback, the frames are played at corresponding time intervals in the order of capture. In multi-media applications, it is desirable to play the audio and video, such that audio frames and pictures that were captured during the same time interval are played at approximately the same time interval.
Encoding standards use time stamps to facilitate playback of audio and video at appropriate times. A decoder compares the times stamps to a system clock to determine the appropriate portions of the audio and video to play. The time stamps are generally examined prior to decoding, because decoding consumes considerable processing power.
In many decoders, there are separate audio and video decoding portions. The audio and video decoding portions take different amounts of time to decode the audio and video data. Generally, the video decoding portion takes longer time to decode the video data. Accordingly, decoding and playing audio and video data with the same time stamp can cause a time lag between the audio and video. This is undesirable to the user.
Further limitations and disadvantages of conventional and traditional systems will become apparent to one of skill in the art through comparison of such systems with the invention as set forth in the remainder of the present application with reference to the drawings.